1. Field of the Invention
The invention relates to a construction and a method for interconnecting a flexible printed circuit and a wiring board and a Liquid Crystal Display (LCD) device and method for manufacturing the same and, more particularly to, the construction and the method for interconnecting, for example, a Tape Carrier Package (TCP) and the wiring board and the LCD device with this interconnection construction and the method for manufacturing the same. The present application claims priority of Japanese Patent Application No. 2001-117553 filed on Apr. 16, 2001, which is hereby incorporated by reference.
2. Description of the Related Art
An LCD device is manufactured by a process of filling a gap between a TFT (Thin Film Transistor) board and a CF (Color Filter) board with liquid crystal to form an LCD panel and then connecting to the LCD panel a TCP mounted with a driver IC (Integrated Circuit) for driving the LCD panel and connecting to the TCP a wiring board for supplying a signal and power.
In this process, conventionally, when interconnecting the TCP and the wiring board, for example, they are aligned with each other by superposing alignment markers, one on the other, such alignment holes made in the TCP and the wiring board respectively beforehand or a pit and a spike formed at a predetermined region of an edge of an input terminal portion of the TCP and an output terminal portion of the wiring board respectively.
These alignment hole and pit (spike) used as the alignment markers are, however, formed by a step different from that for forming a circuit pattern, so that an error occurs in a relative position between the alignment markers and the circuit pattern, thus giving rise to misalignment between the TCP and the wiring board.
Further, by such method of using the pit or the spike as the alignment markers, when the pit is formed, there occurs a decrease in area for interconnecting the input terminal portion of the TCP and the output terminal portion of the wiring board; when the spike is formed, on the other hand, there occurs such an defect that when the input terminal portion of the TCP and the output terminal portion of the wiring board are interconnected, the spike may butt against a mating terminal portion, thus damaging it.
To guard against it, for example, Japan Patent No. 2730572 discloses a method by which when a circuit pattern is formed on a TCP and a wiring board, simultaneously a dummy lead and a dummy land are formed as an alignment marker independently of this original circuit pattern so that the dummy lead and the dummy land may be superposed one on the other for alignment of the two.
By this method, specifically, as shown n FIG. 18A, TCPs 102 are connected to an LCD panel 100 and, for example, rightmost and leftmost TCPs 102 are aligned with a wiring board 101 to then connect it to each of the TCPs 102.
The following will describe a configuration of the TCP 102 and that of the wiring board 101.
As Shown in FIG. 18A, in each TCP 102, at a mounting portion of a tape carrier having insulation and flexibility is mounted a driver IC 104 for driving the LCD panel 100.
The tape carrier 103 is made up of a insulated flexible base film (not shown) and such a circuit pattern (not shown) formed thereon as to include an input terminal portion 105 and an output terminal portion 106.
The input terminal portion 105, as shown in FIGS. 18A, 19, and 21, has a plurality of linear terminals 1051, 1052, . . . , 105n (For example, n=384). Outside the outermost terminals 1051 and 105n are further formed dummy leads 103a, 103a. 
Also, as shown in FIGS. 18A, 12B, 19, and 21, the insulated flexible base film (not shown) is cut at a predetermined region at its both side to form notches 107, 107, in which the dummy leads 103a, 103a are formed so that later described U-shaped dummy lands 113, 113 can be recognized visually.
The notch 107 is specifically formed as a recess so that its upper edge 108 and lower edge 109 may extend perpendicularly to an extension direction (length direction) of linear terminals 1051, 1052, . . . , 105n making up the input terminal portion 105.
The wiring board 101 is, as shown in FIG. 18B, made up of an insulating board 110 and such a circuit pattern formed thereon as to include output terminal portions 111 connected to the input terminal portions 105 of the TCPs 102.
Each of the output terminal portions 111 has n number of terminals 1121, 1122, . . . , 112n that correspond to the input terminal portion 105. Also, as shown in FIGS. 18B, 20 and 22, for example outside the outermost terminal 1121 of the leftmost output terminal portion 111 and outside the outermost terminal 112n of the rightmost output terminal portion 111 are formed the U-shaped dummy lands 113, 113.
The following will describe a method of alignment in connecting a wiring board 101 to each TCP 102.
First, an Anisotropic Conductive Film (ACF) is mounted on each output terminal portion 111 of the wiring board 101, which is then arranged on the back side of the TCP 102 in such a manner that each output terminal portion 111 may face the input terminal portion 105 of each TCP 102.
Next, in both of the outermost TCPs 102, the dummy leads 103a are superposed on the vertical portion of the u-shaped dummy lands 113 in alignment perpendicular to the extension direction of the input terminal portion 105 (output terminal portion 111).
Next, as shown in FIGS. 23 and 24, alignment is performed in the extension direction of the input terminal portion 105 so that the U-shaped dummy land 113 may be put in the notch 107, that the upper edge 108 of the notch 107 may be aligned with an outer upper edge 114 of the U-shaped dummy land 113, and that the lower edge 109 of the notch 107 may be aligned with an outer lower edge 115 of the U-shaped dummy land 113.
Next, by using a heat tool, it is performed to heat the TCP 102 and the wiring board 101 to a predetermined temperature under pressure, thus interconnecting the TCP 102 and the wiring board 101.
According to the above-mentioned conventional technology, however, it is necessary to preserve on the TCP 102 a region for providing the dummy leads 103a, 103a besides the terminals 1051, 1052, . . . , 105n, thus leading to a problem that the TCP 102 must be widened.
This problem in turn leads to another problem that when a number of TCPs 102 are connected on a high-definition LCD panel having a large number of picture elements, the mutually adjacent ones of these TCPs 102 may interfere with each other in some cases
If an inter-terminal pitch is decreased to reduce a width of the TCP 102, on the other hand, there occurs such a problem of short-circuiting, thus deteriorating reliability
In view of the above, it is an object of the invention to provide a construction and method for interconnecting a TCP and a wiring board and an LCD device and method for manufacturing the same that are capable of accurate alignment and reducing a width of the TCP without deteriorating reliabilities of the interconnection.
According to a first aspect of the present invention, there is provided an interconnecting construction for interconnecting a flexible printed circuit and a wiring board, the flexible printed circuit including: a first circuit pattern forced on one face or two faces of an flexible base film and a semi conductor device mounted at a predetermined region of the insulated flexible base film; and said wiring board including an insulated board on one face or two faces of which is formed a second circuit pattern for receiving a signal or transmitting it to the flexible printed circuit, wherein:
the predetermined region of the insulated flexible base film is formed on the insulated flexible base film so as to face the wiring board, constitutes the first circuit pattern, and is cut to form a notch so that a first alignment portion used for alignment of the flexible printed circuit and the wiring board may be recognized visually therethrough; and
based on a positional relationship between the first alignment portion and a second alignment portion that can be visually recognized through the notch, making up the second circuit pattern, and that is used for alignment of the flexible printed circuit and the wiring board, the flexible printed circuit and the wiring board are aligned with each other at least in two different direction therebetween.
In the foregoing first aspect, a preferable mode is one wherein based on a positional relationship between at least part of an edge of the notch and the second alignment portion, the flexible printed circuit and the wiring board are aligned with each other in at least two different directions therebetween.
Also, a preferable mode is ore wherein an input terminal portion or an output terminal portion making up the first circuit pattern and having a plurality of linear input terminals or a plurality of linear output terminals is connected to an output terminal portion or an input terminal portion making up the second circuit pattern and having a plurality of linear input terminals or a plurality of linear output terminals;
the two different directions are an extension direction of the linear input terminals or the linear output terminal portion in the first circuit pattern and a direction intersecting with the extension direction;
the first alignment portion is part of the input terminal portion or the output terminal portion making up the first circuit pattern;
the second alignment portion is part of the output terminal portion or the input terminal portion making up the second circuit pattern and that is connected to the input terminal portion or the output terminal portion respectively making up the first circuit pattern;
the notch has an edge that extends at least in a direction intersecting with the extension direction and the first alignment portion is formed parallel with the extension direction; and
the second alignment portion is formed in such a manner that when the input terminal portion or the output terminal portion of the flexible printed circuit and the output terminal portion or the input terminal portion respectively of the wiring board are aligned with each other accurately, one part of the second alignment portion maybe superposed on the first alignment portion and an edge of another part of the second alignment portion may be aligned with the edge of the notch.
In addition, a preferable mode is one wherein the first alignment portion is part of a most peripheral input terminal or a most peripheral output terminal of the flexible printed circuit of the linear input terminals or the linear output terminals in the input terminal portion or the output terminal portion making up the first circuit pattern; and
the second alignment portion is part of the linear input terminals or the linear output terminals in the output terminal portion or the input terminal portion making up the second circuit pattern and being connected to a corresponding the linear input terminal or a corresponding the linear output terminal in the first circuit pattern.
Furthermore, a preferable mode is one wherein the first alignment portion and the second alignment portion have respective regions with a same width so as to be superposed on each other, in such a configuration that the linear input terminal or the linear output terminal whose part is formed as the first alignment portion is increased in width at least toward a center side input terminal or a center side output terminal in the flexible printed circuit except at the first alignment portion.
According to a second aspect of the present invention, there is provided a interconnecting method for interconnecting a flexible printed circuit and a wiring board, the flexible printed circuit including: a first circuit pattern formed on one face or two faces of an insulated flexible base film and a semiconductor device mounted at a predetermined region of the insulated flexible base film, and said wiring board including an insulated board on one face or two faces of which is formed a second circuit pattern for receiving a signal or transmitting it to the flexible printed circuit, including the steps of:
forming part of the first circuit pattern formed on such a side of the insulated flexible base film as to face the wiring board as a first alignment portion used in alignment of the flexible printed circuit and the wiring board;
forming part of the second circuit pattern formed on the insulated board as a second alignment portion used in alignment of the flexible printed circuit and the wiring board;
cutting the insulated flexible base film at a predetermined region thereof to form a notch through which the first alignment portion can be recognized visually; and
the flexible printed circuit and the wiring board are aligned with each other at least in two different directions therebetween based on a positional relationship between the first alignment portion visually recognized through the notch and the second alignment portion.
In the foregoing second aspect, a preferable mode is one wherein based on a positional relationship between at least part of an edge of the notch and the second alignment portion, the flexible printed circuit and the wiring board are aligned with each other in at least two different directions therebetween.
A preferable mode is one wherein the two different directions are an extension direction of the linear input terminals or the linear output terminal portion in the first circuit pattern and a direction intersecting with the extension direction, and one that wherein includes the steps of:
forming, as the first alignment portion, part of an input terminal portion or an output terminal portion making up the first circuit pattern and having a plurality of linear input terminals or a plurality of linear output terminals;
forming, as the second alignment portion, part of an output terminal portion or an input terminal portion making up the second circuit pattern and having a plurality of linear input terminals or a plurality of linear output terminals.
forming at the notch an edge along the direction intersecting with the extension direction and also forming the first alignment portion in parallel with the extension direction;
forming beforehand the second alignment portion so that when the input terminal portion or the output terminal portion making up the first circuit pattern of the flexible printed circuit and the output terminal portion or the input terminal portion making up the second circuit pattern of the wiring board are aligned with each other accurately along the direction intersecting with the extension direction of the input terminal portion or the output terminal portion making up the first circuit pattern respectively, one part of the second alignment portion and the first alignment portion may be superposed on each other and also an edge of another part of the second alignment portion may be aligned with the edge of the notch; and
aligning the first alignment portion and the second alignment portion with each other and then interconnecting the flexible printed circuit and the wiring board.
Still another preferable mode is one that wherein includes the steps of:
forming, as the first alignment portion, cart of a most peripheral terminal of the flexible printed circuit of the input terminals or the output terminals in the input terminal portion or the output terminal portion making up the first circuit pattern; and
forming, as the second alignment portion, part of the output terminals or the input terminals in the output terminal portion or the input terminal portion making up the second circuit pattern, so as to be connected to the most peripheral terminal of the first circuit pattern.
An additional preferable mode is one that wherein includes the steps of:
providing the first alignment portion and the second alignment portion with respective regions having a same width so as to be superposed on each other and forming the linear input terminal or the linear output terminal whose part is formed as the first alignment portion so that a width of the terminal may be increased at least toward a center side input terminal or a center side output terminal of the flexible printed circuit except at the first alignment portion; and
aligning the first alignment portion and the second alignment portion with each other and then interconnecting the flexible printed circuit and the wiring board.
Still additional preferable mode is one wherein at least a width of the linear input terminal or the linear output terminal whose part is formed as the first alignment portion and a distance between the linear input terminal or the linear output terminal and the adjacent terminal are set beforehand taking into account expansion of the insulated flexible base film when the flexible printed circuit and the wiring board are interconnected.
According to a third aspect of the present invention, there is provided a liquid crystal display device provided with the interconnecting construction according to the first aspect, including;
a liquid crystal display (LCD) panel;
the flexible printed circuit connected to the LCD panel; and
the wiring board connected to the flexible printed circuit,
wherein the semiconductor device mounted to the flexible printed circuit drives the LCD panel, while the wiring board supplies a signal to the flexible printed circuit.
According to a fourth aspect of the present invention, there is provided a liquid crystal display device manufacturing method including the interconnecting method according to the second aspect, including the step of:
connecting the flexible printed circuit to the LCD panel;
and connecting the wiring board to the flexible printed circuit.
With the above configuration, when a flexible printed circuit and a wiring board are interconnected, part of the circuit pattern is used for alignment, thus making it possible to reduce the width of the flexible printed circuit without deteriorating the reliability of the interconnection. It is also possible to give some allowance to the inter-terminal pitch.
In addition, since part of the circuit pattern is used in alignment, alignment can be accurate as compared to a case where an alignment marker is formed in a step different from that for forming the circuit pattern.
Also, since the most peripheral one of the terminals of the input terminal portion of the flexible printed circuit is formed relatively large in width except at a portion used for visual alignment through the notch, it is possible to compensate for a decrease in contact area owing to a shift of this terminal of the flexible printed circuit when the flexible printed circuit and the wiring board are interconnected.
Also, since a width of the terminal whose part is formed as an alignment portion a distance between this terminal the adjacent terminal are set beforehand taking into account expansion of the insulated flexible base film when the flexible printed circuit and the wiring board are interconnected, they can be interconnected accurately to thereby cause, for example, no insufficient interconnection area or no post contact, thus improving reliabilities of the interconnection.